Keep one's head above water!

This idiom means to manage to survive, especially financially.

For example: In my first year after college I tried hard to keep my head above water, and I succeeded.

My neighbors can hardly keep their heads above water, because they have so many expenses.

It also means to keep up with one's work. For example: Jim had taken on so much work, and he could barely keep his head above water. 

Get it?!